I find the hardware support argument far more compelling that diminishing the value of lossless publishing.
In cases where you need lossless, WebP is there. It's close to JPEG XL's performance, sometimes beats it, and is orders of magnitude faster to decode.
Sure, but if companies are going to put in the effort to support a format, you might as well work towards supporting the 'full capabilities' of it, that way it can be used in as many workflows as possible.
You want your camera, photo editing software, colour correction process, etc, to support lossless. One of your final outputs may be for the web where lossless is not important, but there may be others as well (e.g., as a graphic in a video production).
That production pipeline may also be used to generate images for things besides the web, so the creators have the choice of having one set of files used everywhere, or one set for the web and a second set for other things.
That JXL lossless is overkill for the web may be overridden by the fact that people don't want to deal with the hassle of multiple sub-sets of files (i.e., laziness or "efficiency").